DE10021863A1 - Electromechanical actuator - Google Patents

Abstract

The electromechanical actuator has at least a first electromechanical actuator (2) and a second electromechanical actuator (3) which is spatially separated therefrom, and a transmitter body (1) which is seated on the actuators (2, 3), a stroke (dl¶2¶ , dl¶3¶) of the actuators (2, 3) in the direction of the transmitter body (1) is controllable.

Description

The invention relates to an electromechanically drivable Actuator, motors using this actuator and a method for operating the actuator.

In the course of advancing technical development takes place the tendency to have a variety of operations and processes to drive optimally through automation. While in the he most two required links of the required systems - the transducers (sensors) for physical and chemical sizes as well as those required for information processing electronics - through the use of new technologies Considerable progress has been made on the basis of mechanical adjustments still largely required actuators on the well-tried but limited technology electromagnetic actuators.

With an electromagnetic actuator it is slow To realize rotations at high moment, a quick dre electromagnetic motor with a reduction gear shoots combined. This inevitably requires relatively large ones Designs and high weight, long start-stop times (the The rotor's moment of inertia must be accelerated to high speeds ) as well as a not negligible game and Price of the strong reduction gear.

From DE 38 33 342 a piezoelectric Stellan is known drives based on the principle of inverse piezoelectric Effect based. But here the basic problem has to be solved, that only a small drive length can be realized: by the volume change of the piezo effect is typically ma ximal drive lengths of 1/1000 of the piezo actuator dimensions possible, d. H. with typical actuator lengths from 0.5 cm to 5 cm, in particular around 20 µm, there are movement paths from 5 µm to  50 µm available. They also have a high repetition rate of the drive steps set limits, since frequencies in kHz range strong sound emissions occur (20 µm. 1000 / s = 20 mm / s). To realize relative slow rotating (50 rpm) or adjusting (1 cm / s) on is a significant transformation of movement amplitude necessary.

For example, DE 38 33 342 used in addition to a very high Repetition frequency of the movement in the ultrasound range (20- 40 kHz) an amplitude transformation of the primary amplitude through the use of resonant actuators. With the piezoceramic is so with a small movement amplitude at the node of Vibration excited a resonant vibration of a body which causes a typically by a factor at the antinode 50 increased movement amplitude is available. In the Pra However, resonant operation has proven to be critical sen. To achieve a high amplitude transformation sen high quality resonators are used so that the Reso nanz becomes extremely narrow-band. This results in difficult insurmountable difficulties in the control when the Resonance frequency z. B. by temperature changes or changes of the load condition fluctuates. In addition, at to comply with very low tolerances during production.

It is the object of the present invention for a cost-effective, compact and lightweight application urged to provide with little play.

This task is performed by an actuator according to the patent Claim 1, by an engine according to claim 9 and solved by a drive method according to claim 12. Advantageous embodiments are defined in the subclaims acceptable.

At least one electromechanical actuator has this a first electromechanical actuator and one of them  spatially separated second electromechanical actuator. An electromechanical actuator has at least one electromechanical element. Under an electromechanical element is understood as a body in which a volume by applying an electrical signal (current, voltage etc.) is stretched, causing a stroke of the actuator gives.

Examples of electromechanical elements are electrostrics tive elements, magnetostrictive elements (e.g. including egg ner electrical winding) or piezoelectric elements. These elements have in common that they control very precisely are erbar and can apply high pressure forces. Other on the one hand, they are less than the component length Hub dl common that limits their direct application.

There is also a transmitter body on the Ak tutors. An expansion of the actuators in the direction the transmitter body is controllable, e.g. B. by creating egg electrical voltage. The stroke dl of the actuators can transformed by using the transmitter body, d. H. in usually greatly enlarged. The transmitter body acts as a non-resonant operated biactive lever. An output body is in the presence of a friction contact tes carried with the transmitter body.

Through the stroke of the actuators, three functions can be realized be: a pressure on a surface of the transmitter body on the output body to close the friction contact, a drive of the output body with closed friction contact and a loosening of the contact between transmitter body and output body. This z. B. an intermittent Closing the friction contact for gradual loading possible movement of the output body.

It is also the use of several electromechanical actuators drives for driving an output body possible. As well  can meh by means of an electromechanical actuator rere output body are driven.

The control of the stretch is not restricted, so it can separately or coupled. As a rule, the Ak actuators can be controlled electronically.

The advantages for the electromechanical actuator include:

• - high translation of the stroke of the actuators,
• - easy construction,
• - due to the non-resonant design is not a special one Dimensional / tolerance in production required.
• - there are four operating states: counterclockwise, clockwise, Blocking, freewheel adjustable,
• - A rotational speed is flexible, e.g. B. electronically, adjustable,
• - maximum power transmission (rotational speed / Torque) and drive speed is by a Ge ometry adjustment very easily adjustable, d. H. an on motor drive is easily scalable.

The transmitter body is preferably stiff.

It is advantageous if the actuators after a magneto strict, an electrostrictive, or especially one Piezoelectric principle can be driven.

It is easy to manufacture, high reliability and particularly precise control cheap when the actuator ren in the form of a multi-layer piezo actuator, in particular especially in low-voltage technology.

To avoid harmful tensile stresses, especially at ceramic electromechanical elements, it is convenient if the actuators are under pressure.  

It is particularly advantageous if the transmitter body with means of a spring element is pressed onto the actuators, because at the same time the transmitter body fits well on the actuators and a pressure preload of the actuators can be achieved. At the same time, effects are more thermal Expansion can be compensated.

It is also convenient if the transmitter body is wedge-shaped cross-sectional area, with a bottom surface on the actuators, because such an easy controllable and versatile actuator gives.

It is used to reduce abrasion and increase size tion of the friction contact advantageous if the the floor opposite drive tip is flattened.

To ensure good contact between the Trans middle body and the actuators over the entire movement area of the transmitter body, it is favorable if between the actuators and the transmitter body each have a transmission gerelement for improved contact support is available. The Transmitter element can e.g. B. be a spherical disc with seat.

For a motor that has an electromechanical actuator according to the principle described above, is therefore a Movement of an output body by means of one Frictional contact transmitted movement of the transmitter body controllable.

It is advantageous if the motor has an output body has, which is transmitted by means of the friction contact gene movement of the transmitter body is rotatable, for. Legs Wave.

It can also be beneficial if the engine has an output body per, which by means of the friction contact  transferred movement of the transmitter body linearly is bar, e.g. B. a piston or a sheet. The output body can both by the at least one actuator be rotatable and linearly displaceable.

In a method for operating the actuator, a stroke dl _{2 of} the first actuator and a stroke dl _{3 of} the second actuator are periodically changed, so that a regular drive results. But there are also others, e.g. B. non-periodic movements possible.

It is particularly advantageous if the stroke dl _{2 of} the first actuator 2 is set in accordance with the equation dl ₂ = dl ₀ .sin (ω.t), and the stroke dl _{3 of} the second actuator is set in accordance with the equation dl ₃ = dl ₀ .sin (ω.t + ϕ) is set, where dl _{0 is} an amplitude, z. B. represents the maximum stroke. ω corresponds to an angular frequency and ϕ a phase angle. In egg nem piezoelectric actuator, such a stroke can be adjusted by an analog setting of the drive voltage applied to the piezo elements, because the drive voltage and the stroke behave linearly to one another in a good approximation.

To produce a high propulsion of the output body it is advantageous if the phase angle ϕ = 180 ° or ϕ = -180 ° is.  

One area of application for such an actuator is the so-called automated house:

Another area of application is in the field of industrial technology:

Use in automotive technology is also possible:

Another area of application is the autofocus drive in Ka mera lenses (EOS from CANON) in which essentially the Criteria apply extremely quickly, compactly and easily.

Of course, the examples given are by users areas are not conclusive, but only show a few advantageous applications.

In the following embodiments, the actuator schematically detailed.

Fig. 1 shows an embodiment of an electromechanical actuator driven motor,

FIG. 2 shows movements of the driver bit different phase angle φ,

FIGS. 3a to 3c shows actuators with differing chen transmitter bodies,

Fig. 4 shows a rotatably drives by means of the electromechanical actuator NEN rule engine,

Fig. 5 shows a armotor driven by means of the electromechanical actuator's Line,

Fig. 6 shows another embodiment of the rotatably driven motor,

Fig. 7 shows a further embodiment of the rotatably driven motor.

Fig. 1 shows a sectional side view of the (x, y) plane of a motor which can be excited to rotate by means of an electromechanical actuator.

The actuator consists of a transmitter body 1 , a first piezomechanical actuator 2 , a second piezo mechanical actuator 3 , a spring element 4 , and two transmission elements 6 , 7 . A drive body 5 is driven by the actuator from the motor. The output body 5 is here in the form of a rotor R, z. B. a shaft, which is excited to rotate by being carried along with the transmitter body 1 . The electromechanical element of the actuators 2 , 3 is in each case a multilayer piezo actuator using low-voltage technology, the stroke dl of which acts on the longitudinal axis using the known d ₃₃ longitudinal effect.

The transmitter body 1 lies on the first transmission element 6 on the first actuator 2 and on the second transmission element 7 on the second actuator 3 . By means of the tension of the spring element 4 , the transmitter body is pulled by 1 in such a way against the two actuators 2 , 3 that the pressure is approximately in the middle of the working line of the two actuators 2 , 3 . This ensures on the one hand a secure fit of the transmitter body 1 on the actuators 2 , 3 and on the other hand a pressure bias of the piezomechani actuators 2 , 3 is given.

The transmitter body 1 is stiff. With its hardened drive tip S, it can be brought into frictional contact with the rotor R in the area of a contact point Pk.

The piezomechanical actuators 2 , 3 are aligned such that their (positive and / or negative) stroke acts parallel to the y-axis in the direction of the transmitter body 1 .

The actuators 2 , 3 include in addition to the piezo actuator with its electrical connections also a head plate and a foot plate.

A similar control for elongation of both actuators ren 2 , 3 causes a frictional connection of the transmitter tip S on the output body R, a similar control of the actuators 2 , 3 for contraction causes an opening of the friction contact. Uneven control of both actuators 2 , 3 (e.g. elongation of the first actuator 2 and contraction of the second actuator 3 ) causes the drive tip S of the transmitter body 1 to move in the direction of the con tracted actuator 2 , 3 (e.g. of the second actuator 3 ).

The rectified proportion of the movement of the two actuators 2 , 3 thus controls the pressure or the opening and closing of the friction contact, while the difference in proportion controls the drive of the rotor R perpendicular to the stroke direction of the actuators 2 , 3 . The drive tip S carries the rotor R in the same direction. For example, with an elongation of the first actuator 2 and a contraction of the second actuator 3 with simultaneous friction contact, the rotor R is rotated counterclockwise.

If, after reaching the maximum stroke difference between the two actuators 2 , 3, the transmitter body 1 is replaced by loosening the contact to the rotor R at the initial position, an intermittent drive results from the rotor R.

Fig. 2 shows one possible movement trajectory of the contact tip in the S (x, y) plane as a function of a phase angle φ. For this purpose, the stroke dl _{2 of} the first actuator 2 and the stroke dl _{3 of} the second actuator 3 according to the equations

dl ₂ = dl ₀ .sin (ω.t)

dl ₃ = dl ₀ .sin (ω.t + ϕ) [1]

controlled, where dl ₀ here represents the maximum stroke of the two actuators 2 , 3 and ω an angular frequency. For some applications, a different stroke or maximum stroke dl _{0 of} the individual actuators 2 , 3 can also be advantageous.

A movement according to Eq. [1] is in a piezoelectrically driven actuator analog to a periodic control voltage U ₂ or U ₃ on the first actuator 2 or on the second actuator 3 with the same frequency

U ₂ = U ₀ .sin (ω.t)

U ₃ = U ₀ .sin (ω.t + ϕ). [2]

With a phase shift of ϕ = 180 ° or -180 ° (against directional control) there is an ellipse as the movement curve of the drive tip S. The given deviation from the circular shape can be adjusted by the geometry of the transmitter body 1 . A phase angle ϕ = 180 ° or -180 ° corresponds to a maximum speed or translational speed of the motor.

The size of the movement of the drive tip S in the x-direction (“x stroke”) can be set directly by a choice of the geometry of the transmitter body 1 , in particular by the ratio of height to width. This makes it possible for the x stroke of the transmitter body 1 to be many times larger than the maximum stroke dl of the actuators 2 , 3 . This corresponds to a stroke ratio with a change in the direction of movement. The actuators 2 , 3 are usually advantageously only slightly bent, especially if the transmitter elements 6 , 7 are freely movable.

As can be seen from this figure, the movement curve causes a soft placement of the drive tip S on the drive body 5 , R, S. Thus, the problem known in previous monomodal motor principles and difficult to remediate problem of wear on the friction contact does not occur significantly Appearance.

In the event of deviations from these values of the phase angle ϕ, there is a drive of the output body 5 , R, S with a reduced speed. With a phase position of ϕ = 0 ° there is no drive, although the friction contact is opened in the meantime. This allows the implementation of a free running condition (active unblocking) in an electromechanical engine, which otherwise blocks the movement with the maximum holding torque when switched off.

Other than sinusoidal control voltages are also possible. To implement a three-dimensional movement curve, it is also possible, for example, to equip a transmitter body 1 , 1 ', 1 "with more than two actuators 2 , 3 or to tilt actuators 2 , 3 against one another.

FIGS. 3a to 3c respectively show an actuator 1, 1 ', 1 "analogous to FIG. 1, in which the lengths of the sides of the gene schrä transmitter body 1, 1 now" 1 "are different from are guided.

FIG. 3b shows an actuator 1 which corresponds to the actuator 1 of Fig. 1.

Fig. 3a shows, in contrast, an actuator that has egg NEN transmitter body 1 'with shortened oblique sides to change the ratio of height to width. This results in a higher power transmission and a lower speed at the drive tip S 'compared to the actuator in Fig. 3b. In order to ensure the frictional contact with higher power transmission, the drive tip S 'is also made wider than in Fig. 3b.

Fig. 3c shows an actuator that has a transmitter body by 1 "with extended oblique sides. This gives it a reduced power transmission at high speed compared to the actuator in Fig. 3b.

From Figs. 3a to 3c shows that the maximum rotation speed / torque of the drive tip S, S ', S "by a choice of geometry of the transmitter body 1, 1', 1" can be set flexibly. Therefore, the actuator is easily scalable, for example by simply replacing the transmitter body 1 , 1 ', 1 ". The effort for adapting to different drive situations is very small, and adapting the motors to the required speed or torque or a linear feed possible.

In addition to changing the dimensions of the transmitter body 1 , 1 ', 1 ", a shape of the transmitter body 1 , 1 ', 1 " can be changed. For example, a transmitter body 1 , 1 ', 1 "with different drive tips S, S', S" can be used who, as a comparison between FIGS . 3a and 3b shows. A transmitter body 1 , 1 ', 1 "with a different shape of the cross-sectional area, for example angular, round, chamfered or also arbitrarily shaped, can also be used.

This is e.g. B. useful if the actuator from a bi directional drive (left / right) on a unidirectional len drive (only left / only right).

Fig. 4 shows a sectional side view of a rotary motor analogous to Fig. 1, in which the rotor R is guided in the form of a shaft rotatably mounted about its longitudinal axis I.

The rotor R is, like other output bodies 5 , in applications usually under load. As a result, a not inconsiderable driving torque can be exerted on it. In contrast, there is the intermittent drive by the actuator 1 . In some cases, the moment of inertia of the rotor R is sufficient to avoid turning back during the opening phase of the friction contact. If this is not the case (e.g. with very slowly rotating and / or heavily loaded motors), you can:

• - either at least a second actuator is used be a 180 ° phase-shifted drive of the Rotor S causes or
• - The rotor R can be locked in the opening phase by means of a further actuator 8 or another brake. Such an embodiment of a motor shows, for. B. Fig. 6.

The same considerations apply to a linear motor.

Fig. 5 shows a side view of a linear motor in which a linear movement in the x direction (symbolized by the arrow) of a general linkage G, which is guided by two bearings L, can be realized by means of the electromechanical actuator. The linkage G can be, for example, a shaft or a flat band. It is also possible to attack several actuators on an output body ( 5 , R, S), for example to increase the torque or for simultaneous rotary and linear movement.

Fig. 6 shows an oblique view of a design of a motor for the realization of slowly rotating and heavily loaded drives. The two actuators 2 , 3 cause, as described above, the rotation of the output body R, which is in the form of a roller. An additional actuator 8 is used for locking purposes during the friction contact open at the front end.

Fig. 7 shows a sectional side view of the (x, y) plane a further embodiment of a motor in which an output body 5 in the form of a shaft can be excited to a rotary movement by means of an electromechanical actuator.

In contrast to the motor from FIG. 1, the shaft 5 now passes between the actuators 2 , 3 in order to save space. The transmitter body 1 * is pressed by a spring element 4 held under compressive stress on the transfer elements 6 , 7 .

Claims (14)

1. Electromechanical actuator, having
at least a first electromechanical actuator ( 2 ) and a second electromechanical actuator ( 3 ) spatially separated therefrom,
a transmitter body ( 1 ) seated on the actuators ( 2 , 3 ),
a stroke (dl ₂ , dl ₃ ) of the actuators ( 2 , 3 ) in the direction of the transmitter body ( 1 ) being controllable. 2. Electromechanical actuator according to claim 1, in which the actuators ( 2 , 3 ) can be driven according to a magnetostrictive, an e-electrostrictive or in particular a piezoelectric principle. 3. Electromechanical actuator according to claim 2, wherein the actuators ( 2 , 3 ) are in the form of a multi-layer piezo actuator. 4. Electromechanical actuator according to claim 3, wherein the actuators ( 2 , 3 ) are under a pressure bias. 5. Electromechanical actuator according to claim 4, wherein the transmitter body ( 1 ) is pressed by means of a spring element ( 4 ) on the actuators ( 2 , 3 ). 6. Electromechanical actuator according to one of the preceding claims, in which the transmitter body ( 1 ) has a wedge-shaped cross-sectional area, wherein it rests with a bottom surface (B) on the actuators ( 2 , 3 ). 7. Electromechanical actuator according to claim 4, in which the drive tip (S) opposite the bottom surface (B) is flattened.   8. Electromechanical actuator according to one of the preceding claims, in which between the actuators ( 2 , 3 ) and the transmitter body ( 1 ) each have a transmitter element ( 6 , 7 ) for improved contact support. 9. Motor, comprising an electromechanical actuator according to one of the preceding claims 1 to 8, in which a movement of an output body ( 5 ) can be controlled by means of a movement of the transmitter body ( 1 ) transmitted by a friction contact. 10. Motor according to claim 9, wherein the output body ( 5 ) is rotatable by means of the movement of the transmitter body ( 1 ) transmitted by the friction contact. 11. Motor according to claim 9 or 10, wherein the output body ( 5 ) by means of the friction contact transmitted by the movement of the transmitter body ( 1 ) is linearly slidable. 12. The method for operating the actuator according to one of claims 1 to 8, in which a stroke (dl ₂ ) of the first actuator ( 2 ) and a stroke (dl ₃ ) of the second actuator ( 3 ) is changed periodically. 13. The method according to claim 12, wherein the stroke (dl ₂ ) of the first actuator ( 2 ) according to the equation
dl ₂ = dl ₀ . sin (ω. t)
is set, and the stroke (U ₃ ) of the second actuator ( 3 ) according to the equation
dl ₃ = dl ₀ . sin (ω. t + ϕ)
is set, where dl _{0 represents} an amplitude, ω a Kreisfre frequency and ϕ a phase angle. 14. The method according to claim 13, wherein the phase angle (ϕ) is 180 ° or -180 °.